Online media and marketing agency Federated Media Publishing and Automattic Inc., which runs the popular WordPress blog platform, announced a partnership Wednesday to sell advertising potentially across nearly 25 million websites.

Brown was introduced to the audience at the Palace Hotel by Federated founder and chairman John Battelle, a principal organizer of the Web 2.0 event, an annual industry event that is co-sponsored by Federated Media.

“I’ve been working on this for seven years,” said an excited Battelle after the news broke.

Automattic and Federated Media are both San Francisco companies that launched in 2005 and have achieved considerable traction.

Automattic’s WordPress software supports 25 million blogs with a combined readership of 300 million unique visitors per month -- a total of 15 percent of the web sites on the Internet, Schneider said.

Despite having such scale, outside estimates of Automattic’s revenue have never been particularly large. The company, which has various products, has not disclosed financial details.

Federated Media has been more open about its revenue, which Brown last month told the San Francisco Business Times was on track to hit between $90 million and $100 million this year.

Brown, who was named to replace Battelle as CEO in February, said Federated Media had plans to expand its editorial offerings and the technology it uses to target conversations on the web, and that it would acquire a few companies over the next year,

Then earlier this month Federated Media bought Lijit Networks Inc., a similar company in Boulder, Colo.

Brown said the Automattic-Federated Media partnership will potentially give advertisers access to 600 million people -- it’s opt-in for publishers and initially available only in the United States -- providing a real alternative to big players like AOL, Google (NASDAQ: GOOG) and Yahoo (NASDAQ: YHOO).